In semiconductor design, the operating characteristics of integrated circuits are commonly temperature dependent. It is generally required to characterize, validate, and/or calibrate a set of product specifications in respect to the die temperature. This requires some procedure to measure die temperature during test with appropriate accuracy.
As the inventors hereof have recognized, to perform high-precision temperature-related specifications, a highly-accurate method to measure die temperature is needed.
Solutions based on external temperature sensors, such as thermocouples, commonly provide poor measurement accuracy of die temperature and long measurement delays, typically worse than +/−7° C. This is mainly due to the significant thermal gradient between the measurement point of interest (silicon junction) and the sensor locus (outside package), This error is higher on System-on-Chip (SoC) products with high power dissipation. Solutions based on fully integrated temperature sensors are not sensitive to thermal gradients beyond the silicon interface, but are commonly limited by the complexity of the measurement and signal-conditioning circuitry that may be completely integrated.
Another factor that compromises the precision of internal temperature sensors is that their output is commonly accessible through a pad that is subject to leakage effect. Leakage currents will create signal offsets that result in measurement errors.
To address these, and other problems, the inventors hereof have recognized a need for providing the measurement of die temperature during factory tests (as a manufacturing resource). The inventors have also recognized a need for more accurate methods to measure die temperature in the field (as a customer feature). Accordingly, the inventors hereof have developed systems and methods for measuring the die temperature of integrated circuits using self-referenced, high-accuracy temperature sensors.